A. {2, 1, 6}
{-1, 0, -4}

B. {0, -1, 2}
{ 2, -1, 6}

C. {6, -3 18}
{-6, 2, -20}

D. They are all equivalent

NONE of the matrices are equivalent to the given augmented matrix above nor are any pair of the given matrices equivalent to each other.

Matrix C comes VERY close to be equivalent to the given matrix as can be seen by dividing the top row of C by 3 and the bottom row by 2.

This yields the matrix :
{2, -1 6}
{-3, 1, -10}

which is obviously NOT equivalent to the given matrix but very close.
To make these matrices equivalent you'd need of course to add a minus to the 10 in the top matrice or delete the minus from the 20 in C. (In both cases the equivalence is trivial)

The other matrices don't come close to being equivalent to the given one as can be seen by finding the "row spaces" of the matrices.
(Matrices are equivalent if and only if their "row spaces" are equal.)

For example the row space of A is t(-4,14,1) and of the top matrix is t(16,38,1) i.e. the row spaces are generated by linearly independent vectors and therefore the matrices are not equivalent.

(I won't elaborate on this, since the question is flawed and it is not clear if this is required)